PROJECT SUMMARY Stem cell therapy represents a promising strategy in regenerative medicine. However, live cells need to be carefully preserved and processed before usage. In addition, cell transplantation carries certain immunogenicity and/or tumorigenicity risks. The development of cell-free and non- living therapeutics derived from stem cells has the potential to revolutionize current regenerative medicine practice. Mounting lines of evidences indicate that stem cells exert their beneficial effects mainly through the secretion of pro-regenerative factors. Based on this, we fabricated ?synthetic cardiac stem cells (synCSCs)? by encapsulating cardiac stem cell-secreted factors in a biodegradable polymer block. In a mouse model of myocardial infarction (MI), intramyocardial injection of synCSCs led to preservation of viable myocardium and augmentation of cardiac functions similar to real CSC therapy in immunodeficiency mice with myocardial infarction by permanent vessel ligation. Despite the successful proof of concept, a big challenge is the effective delivery of synthetic cells to the heart. The present proposal represents a logic progression from our previous work. Here we will be developing and testing a new entity: an artificial cardiac patch (artCP) formed by embedding synCSCs into decellularized myocardial extracellular matrix (ECM). Our studies will extend from the previous rodent acute MI model to a chronic heart failure model in both small/large animals. The overarching hypothesis is that artCPs can further improve the efficacy of synCSC therapy in rats and pigs with chronic heart injury. Aim 1 is to fabricate artCPs and determine in vitro potency. Aim 2 is to demine the safety and efficacy of artCP therapy in a rat model of chronic infarct. Aim 3 is to translate the findings into a clinically relevant porcine model of advanced cardiomyopathy. Our study will form the foundation for an innovative and ?off the shelf? therapy based on stem cell factors and myocardium ECM. The cell-free nature of our approach is more readily translatable to the clinic. Although this particular grant application targets the heart and cardiac stem cells, our approach represents a platform technology that can be applied to the creation of multiple types of synthetic stem cell and ECMs for the repair of various other organs.